feat!(gcp_stackdriver_logs sink): Support more fields

[fbs]

draft: I'm not sure this is the right approach, as its a breaking change and doesn't follow the pattern of other fields, like severity key. However, using a remap to get events in the right format seems flexible than having a bunch of 'xx key' config options, for which you still need a remap to provide a default/fallback.

If the approach is ok I'll add more fields, fix up the tests and the changelog.

Summary

The LogEntry1 type supports a lot more fields than are currently supported by the sink. This change adds support for labels, but more fields can be added the same way.

Additionally this removes the timestamp from the message, if set, instead of having it in both the 'timestamp' field, as well as part of the message payload.

It also changes the payload type from json to text if the message is only a string. This makes the GCP search queries simpler, e.g. textPayload: "some message" instead of jsonPayload.msg: "some message".

Change Type

• Bug fix
• New feature
• Non-functional (chore, refactoring, docs)
• Performance

Is this a breaking change?

• Yes
• No

How did you test this PR?

Sending logs to GCP

Does this PR include user facing changes?

• Yes. Please add a changelog fragment based on our guidelines.
• No. A maintainer will apply the "no-changelog" label to this PR.

Checklist

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References

• Improve stackdriver logs sink #22374

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